Rose Anthracnose
Sphaceloma rosarum · Fungal
Small, sharp-edged spots that drop out of the leaf, leaving a "shothole" pattern. Often confused with mild black spot.
Symptoms
Small (2–6 mm) dark purple to red-brown leaf spots with sharply defined, almost white centers; older spots drop their centers, leaving the leaf looking shot through with holes. Distinguished from black spot by the cleaner edges and the dropped centers. Spots may also occur on stems and petals.
How it progresses
Less aggressive than black spot but unsightly; can defoliate in a wet year.
Conditions that favor it
Spores germinate in 6+ hours of leaf wetness at 60–75 °F. Spreads by splashing rain. Overwinters on canes and fallen leaves.
Organic & cultural treatment
Sanitation as for black spot. Copper sprays. Most black spot programs also handle anthracnose.
Chemical treatment (when warranted)
Same fungicides as for black spot.
Prevention
Sanitation, airflow, and drip irrigation. The same playbook as black spot.